The present invention relates to an air conditioner, particularly for a motor vehicle, having a compressor, a condenser (gas cooling apparatus), an expansion valve, an evaporator, a collector and an internal heat exchanger.
In a known air conditioner of the initially mentioned type (European Patent Document 0 611 926 B1), the internal heat exchanger is combined into a constructional unit with the evaporator and the expansion valve. It is also known from U.S. Pat. No. 5,544,498 and European Patent EP 0 710 808 A1, for example, to combine the internal heat exchanger with the evaporator or with the expansion valve in such an air conditioner. By way of the internal heat exchanger, heat is transferred from the compressed coolant to the expanded coolant. As a result, the performance number, that is, the ratio of the refrigerating capacity to the driving power of the air conditioner, is clearly improved. The internal heat exchanger, which is combined with the evaporator and/or the expansion valve, leads to an increased space requirement inside the dashboard of a vehicle; the available space inside the dashboard, however, is very limited.
In most cases, air conditioners for motor vehicles are used without an internal heat exchanger. The air conditioners which operate with conventional refrigerants (R 134a) are normally operated such that the critical pressure of the refrigerant is not exceeded. Heat supply and heat removal take place in the two-phase region by evaporation and condensation of the refrigerant. In air conditioners for vehicles which contain the refrigerant R 744 (CO.sub.2), the pressure of the refrigerant in the system may become larger than the critical pressure of the refrigerant. A liquefaction of the refrigerant will then no longer take place. In order to obtain a performance number in such an air conditioner which is equal to or better than the performance number of the air conditioners operated by way of conventional refrigerants, an internal heat exchanger is provided. In such an air conditioner (German Patent Document DE 196 35 454 A1), it is known to combine the internal heat exchanger with a collector.
It is an object of the invention to provide an air conditioner which is particularly suitable for the R 744 refrigerant and in which the internal heat exchanger is housed in an advantageous manner.
This object is achieved by combining the internal heat exchanger with the condenser (gas cooling apparatus).
The condenser is normally housed in the engine compartment of the vehicle with which it is associated, since slightly more space is available than in the area of the dashboard; consequently, the housing of the internal heat exchanger in the area of the condenser presents no major problems.
In one preferred embodiment of the invention, the internal heat exchanger is integrated in the collector which is combined with the condenser (gas cooling apparatus). If the refrigerant lines are guided correspondingly, then it is possible to construct the collector as a high-pressure collector or as a low-pressure collector. By combining the collector having the integrated internal heat exchanger with the condenser (gas cooling apparatus), and particularly by forming a constructional unit containing these three elements, cost and safety advantages are achieved. Fewer connection points are required in the refrigerant circulation system so that the danger of a loss of refrigerant is reduced.
Additional characteristics and advantages of the invention are found in the following description of the embodiments illustrated in the drawings.